Accessory Gene Regulator Types of Staphylococcus aureus Isolated in Gorgan, North of Iran.

BACKGROUND

Staphylococcus aureus is a gram-positive bacterium that has remained a persistent pathogen, causing infections such as endocarditis, meningitis, and toxic shock syndrome in humans. The accessory gene regulator (agr) system of Staphylococcus aureus is responsible for controlling the expression of many genes that code for virulence factors. In this study, we assessed the S. aureus agr Group, based on their source of isolation, in Gorgan, North of Iran.

MATERIALS AND METHODS

DNA of 194 S. aureus isolates was extracted by lysozyme-phenol chloroform method, which included 85 clinical samples, 58 samples which were isolated from noses of health care workers and 51 cases which were obtained from food products in Gorgan, northern Iran. PCR-based assays were used to evaluate agr locus nucleotide polymorphism for the identification of agr specificity Group. Distributions of each agr Group were determined and comparison between different sources was assessed by X(2). A p-value of <0.05 was considered as significant.

RESULTS

The majority of isolates belonged to agr Group I (43.3%), followed by agr Group III (28.87%), agr Group II (22.68%), and agr Group IV (5.15%). In our study, a majority of S. aureus isolates were recovered from health care workers and food product specimens were of agr Group I and isolates which were recovered from patients were of agr Group III. These differences were statistically significant (P=0.005). There was no statistical difference between the source of isolation of clinical samples of S. aureus and agr type.

CONCLUSION

Agr Group I was predominant among health care workers and food product specimens in Gorgan, North of Iran, but in strains which were isolated from patients, agr Group III was predominant. Investigating the possible role of agr Group III in Staphylococcus aureus infection in future studies is recommended.